Due to superior wear and corrosion resistance, polymer-lined pipes and fittings have been used in many aggressive slurry services in the oil sands mining industry. Rubbers and polyurethanes are the main polymeric liner materials currently being used. Liner thickness is commensurate with length of the pipe run, and can exceed 1 inch in very long pipe runs. However, liner wear still occurs, and in particular, the inlets and outlets often experience the most serious liner wear. This is mainly due to pipe misalignment where the resultant step change in pipe inside diameter (ID) can cause so-called ‘liner wash-out’ due to either direct impingement from the slurry particles (prior art FIG. 1A) or slurry turbulence. The wash-out area is localized, normally less than a foot from the pipe connection between the upstream pipe (UP) and the downstream pipe (DP). Liner wear is often accelerated in that localized wear zone, resulting in early retirement of the spool even though most areas are in serviceable condition.
When two different piping materials having significantly different wear rates are connected side by side, ID mismatch can develop during pipe operation and this can also lead to accelerated liner wear near the pipe connection. Piping components can have different geometries (i.e. elbows vs. straight spools) having different wear profiles and rotation strategies and in this case, step change in ID can appear after pipe rotation. It is challenging to achieve ID match throughout the pipeline during operation.
Currently, field repair kits are used to address the localized liner wear. Repair kits are composed of two-part mixing components: once they are mixed together and applied onto the damage area, solid repair patch is formed after curing. Proper surface preparation (solvent cleaning, mechanical buffing on the liner adjacent to the damage area), good environmental control (temperature, humidity), and skillsets of the applicators are key to success. Since repairs are conducted in the field during outages where limited time and resources are available, it is challenging to achieve consistent repair quality. Accordingly, there remains a need for more efficient and reliable technologies to achieve smooth ID transition in polymer-lined pipeline.
When there is step-change in inside diameter at pipe connection due to different inside diameters (IDs) of mating pipes (prior art FIG. 1B), transition rings can be used for smooth ID transition. Transition rings use abrasion and wear resistant alloy linings such as tungsten carbide, which introduces significant cost increase. Also, transition rings are flange-connected, thereby incorporating more pipe connection points with a resulting increase in the possibility of ID mismatch.